Counterfeiting of bank notes, and other valuable documents, including but not limited to bonds, drivers' licenses, birth certificates and gift certificates, is a well-known problem. Counterfeiters have become more and more sophisticated in their methods as a result of technological advances. Issuers of bank notes and other valuable documents must therefore continually enhance the security of such documents as technology permits. A significant problem also exists with respect to counterfeit credit cards and other electronic transaction cards.
Similarly, many industries are plagued with the problem of counterfeited or simulated goods. Counterfeited goods are common in the music, movie, art, apparel, ticketing and other industries. As an example, “bootleg” compact discs, videos and DVD's are quite common, as are “knock off” designer hand bags, watches and clothing. Counterfeit tickets are routinely sold to unsuspecting members of the public hoping to attend sporting events, theater and concerts.
Increased sophistication of counterfeiters in recent years has lead to increasingly accurate reproductions of original products and documents. The wide-spread availability of digital imaging technology, sophisticated color reproduction equipment, particularly in connection with the internet, has made it increasingly easy for counterfeiters to reproduce protected works (for instance, realistic looking box art on a DVD) which the ordinary consumer typically cannot detect as counterfeit.
In response to this threat, manufacturers and publishers have attempted to devise ever more sophisticated anti-counterfeiting measures. Hologram security and authentication devices have had much success countering counterfeiters in recent years. A manufacturer wishing to authenticate a product with a hologram (defined herein as including holograms and other similar diffractive devices such as kinegrams, diffraction gratings, excelgrams and other optically variable devices) would permanently affix a hologram to the product. Alternatively, the hologram could be affixed to packaging containing the product to authenticate the material within. Similarly, a hologram could be permanently affixed to the face of a bank note, driver's license, theater ticket or other document of value. Typically the hologram is not removable without damaging it or the surface to which it is affixed. The counterfeiter would thus have to reproduce a hologram to obtain a convincing counterfeit article. Use of sophisticated holograms makes the production of convincing counterfeits even more difficult.
Unfortunately, some sophisticated counterfeiters now have the means to approximate many holograms. In the future it is likely that counterfeiters will gain access to ever more sophisticated technologies, and therefore become increasingly able to counterfeit even more sophisticated holograms.
Digital watermarks have been in existence since approximately 1995, and have been used commercially in recent years. Digital watermarks are security devices which embed ownership, authorship, origin, distribution, customer, purchase or any other type of commercially-relevant or security-relevant information onto or within an image or object.
Previously, digital watermarking has been employed as a technique to protect against unauthorized copying and distribution of digital content. In general, “digital watermarking” comprises an act of embedding information (referred to as a “watermark”) into the data set in an unobtrusive way so that the quality of the data set is not reduced, but the watermark can be extracted as the data set is being used. This is typically accomplished by placing the watermark into a noise band of the data set. In the context of a visual image such as a electronic photograph file, the “noise band” may include, for example, a few least significant bits associated with the color of each pixel of an image.
In addition, a watermark may be embedded so as to be resilient to various manipulations of the data set such as, for example, photocopying, scanning, resizing, cropping and color manipulation. Of course, the selected degree of resiliency is determined by the amount of information that can be embedded in a data set. As an illustrative example, if resiliency to cropping is desired, a watermark is placed in a redundant fashion in different portions of the data set. If such cropping resiliency is not desired, bandwidth consumed by such redundancy may be allocated to improve quality of the data set.
Digital watermarks may exist either in perceptible or imperceptible form, depending on the purpose they are meant to serve. Use of the term “imperceptible” refers to digital watermarks which cannot be detected by the untrained naked eye. Imperceptible digital watermarks must nevertheless be detectable by some other means, e.g., be machine readable, to be of value.
Perceptible and imperceptible digital watermark can act as a deterrent to theft and counterfeiting in different ways. Perceptible watermarks alert the viewer that the document or image is protected, and diminish its commercial value. Imperceptible watermarks increase the likelihood of successful prosecution and may also act as a deterrent if the criminal is sufficiently computer literate. The table below shows some of the known primary (P) and secondary (S) benefits of digital watermarking:
PurposePerceptibleImperceptibleDetermine ownershipPPValidation of intended recipient—Pnon-repudiable transmission—PDeterrence against theftPPmeta level, content labeling—PDiminish commercial value withoutP—diminished utilityDiscourage unauthorized duplicationPPAuthenticationSPIdentify document sourcePPNetwork patrolling (e.g., on Web)SPrights management (e.g., “copiesSPremaining”)
As noted above, until now, the use of digital watermark technology was employed most often for the protection of digital images existing in electronic form. Many of the uses listed above, for instance, apply only to electronic images. To the extent that digital watermarking technology has been applied to physical objects such as printed art work, this has always been accomplished with an ink-based digital watermark. Ink-based digital watermarks, although useful in certain applications, ultimately do not provide the highest available level of anti-counterfeit protection. This is because printed digital watermarks are susceptible to counterfeiting without the use of holographic technologies.
The invention also relates to a tracking system. Product tracking systems are also known. For instance, the ubiquitous bar code label on many products permits the compilation of a limited amount of product and customer information.
In several ways, however, bar coding is quite limited. Initially, bar coding is visible to the naked eye. There is nothing about the bar code which is imperceptible or “covert”. Thus the ability of a bar code to provide the security features discussed above is limited. A bar code also cannot be incorporated into a hologram without comprising the optical and aesthetic integrity of the hologram. Further, a bar code cannot encode the same amount of information as a digital watermark. Thus, unlike a bar code, a digital watermark can be tailored to individual products (e.g., each watermarks might encode a different product serial number).